In prior art processes for diffusing boron into a silicon wafer, the steps of deposition of a boron glass formation and the diffusion of the boron into the silicon lattice are accomplished at a single temperature, such as 1,000.degree. Centigrade, for example. It has been found that this conventional approach is difficult to control because the resultant sheet resistance is dependent on the simultaneous uniformity of temperature, gas mixing, reaction rate, and interaction with the wafers. In order to achieve the desired uniformity, the conventional deposition process which utilizes a boron chloride gas supply, employs widely spaced wafers disposed in a furnace tube so that load sizes and thus process capacity are limited.